WAKE-UP CIRCUIT, WAKE-UP CIRCUIT ARRANGEMENT, AND WAKE-UP METHOD FOR ACTIVATING AN ELECTRIC OR ELECTRONIC FUNCTIONAL GROUP

摘要

The invention relates to a wake-up circuit (1) for activating an electric or electronic functional group (4), said wake-up circuit (1) having a switch input (26), which is galvanically separated from the functional group (4), in order to connect a switching element (6) that switches the functional group (4). According to the invention, the wake-up circuit (1) has a coupling transformer (18) with a secondary side (22) which is electrically connected to the switching input (26) and with a primary side (20) which is galvanically separated from the secondary side (22) and inductively coupled to the secondary side (22). The wake-up circuit (1) further has a multivibrator (12), which is electrically connected to the primary side (20), for providing electric energy with a peak power to the primary side (20) of the coupling transformer (18) in a time-discrete manner. The wake-up circuit also has a trigger stage (14) for scanning the effective impedance on the primary side (20) of the coupling transformer (18), said impedance being dependent on the switch position of the switching element (6) on the secondary side (22), and for controlling the functional group (4) dependent on said scanned effective impedance. The invention thus allows the switching of the functional group (4) by means of a passive switching element (6) with a low power consumption of the wake-up circuit (1).